The present invention relates to a motor driving device for driving a plurality of driven sections which are driven with different operation timing sequences in a printer, and which are, for example, an automatic paper feeding mechanism and a form feeding mechanism or the like to carry out the line feed of cut forms being fed toward a printer body by means of the automatic paper feeding mechanism in the printing position.
Conventionally, as a driving motor for an automatic paper feeding mechanism of cut forms such as letter-size or legal-size paper sheets in a printer, and as a motor to drive a form feed mechanism for carrying out the line feed of the cut forms in the printing position, namely a platen mechanism, a polyphase stepping motor has been separately adopted, respectively. Transistors, as a phase current flowing element, for example, are connected to driving circuits to control two kinds of said stepping motors, each respective phase coil of the respective stepping motors, and the switching of the respective transistors is carried out in accordance with the drive timing of the automatic paper feeding mechanism or the form feeding mechanism, for example, corresponding to a control signal which is outputted from a microcomputer and the like, and these stepping motors have been driven by causing an excitation current to flow in the phase coils to which the transistors are connected. Accordingly, since the transistors are connected to the respective coils of the stepping motors one to one to cause the excitation current to successively flow in the respective phase coils, the same number of transistors are required as the total phase number of the respective stepping motors.
As mentioned above, since the phase current flowing elements such as transistor to cause the excitation current to flow in the respective phase coils are required in the same number as the total phase number of the respective stepping motors in the stepping motor driving circuit in a conventional printer, there are problems, such as high cost, and the space occupied by the current flowing elements on the printed circuit board of the printer is large, and it is difficult to reduce the size of the printed circuit board and therefore there is a limit to the printer compactness.